1. Field of the Invention
The present invention relates to an antenna installed in a mobile telecommunication terminal, and more particularly to a built-in antenna capable of processing wide-band or multi-band signals while occupying a minimum space in the mobile telecommunication terminal.
2. Description of the Related Art
Recently, a rising demand for wireless devices installed inside mobile telecommunication terminals has led to diversity in frequency bands used in an antenna of such a terminal. Specifically, frequency bands currently used in the mobile telecommunication terminals include 800 MHz to 2 GHz (for mobile phones), 2.4 GHz to 5 GHz (for wireless LAN), 113.56 MHz (for contactless RFID), 2.4 GHz (for Bluetooth), 1.575 GHz (for GPS), 76 to 90 MHz (for FM radio), 470 to 770 MHz (for TV broadcasting) and other bands for ultra wideband (UWB), Zigbee, Digital Multimedia Broadcasting (DMB) and the like. The DMB band is classified into 2630 to 2655 MHz for satellite DMB and 180 to 210 MHz for terrestrial DMB.
Meanwhile, the mobile telecommunication terminals have been faced with demands for smaller size, lighter weight and various service functions as well. To meet such demands, the mobile telecommunication terminals tend to employ an antenna and other components which are more compact-sized and multi-functional. Furthermore, increasingly the mobile telecommunication terminals are internally equipped with the antenna. Therefore, to be installed inside the terminals, the antenna needs to occupy a very small space, while performing with satisfactory capabilities.
FIG. 1 is a configuration view illustrating a conventional built-in Planar Inverted F Antenna (PIFA) 10.
The PIFA 10 is an antenna designed for installation in a mobile telecommunication terminal. As shown in FIG. 1, the PIFA 10 generally includes a planar radiating part 11, a shorting pin 12 connected to the radiating part 11, a coaxial line 13, and a ground plate 14. The radiating part 11 is fed with current via the coaxial line 13 and short-circuited to the ground pate 14 by the shorting pin 12 to achieve an impedance match. The PIFA 10 needs to be designed by considering the length L of the radiating part 11 and height H of the antenna in accordance with the width Wp of the shorting pin 12 and width W of the radiating part 11.
The PIFA 10 is characterized by directivity. That is, when current induced to the radiating part 11 generates beams, a beam flux directed toward a ground surface is re-induced to attenuate another beam flux directed toward the human body, thereby improving SAR characteristics and enhancing intensity of the beam flux induced to the radiating part 11. The PIFA operates as a rectangular micro-strip antenna, in which the length of a rectangular panel-shaped radiator is substantially halved, thereby realizing a low profile structure. Moreover, the PIFA is installed inside the terminal as a built-in antenna so that the terminal can be designed with an aesthetic appearance and significantly withstand external impact. The PIFA 10 has been upgraded considerably in line with a multi-functional trend.
FIG. 2 is a configuration view illustrating a conventional ceramic chip antenna 20.
Referring to FIG. 2, inside the conventional ceramic chip antenna 20, conductors 22 and 23 for radiating are formed via a lamination process. In FIG. 2, the conductors 22 and 23 are formed in a spiral coil shape, which, however, can be modified variously. The conductors 22 and 23 are comprised of a parallel strip line 22 printed in parallel with an undersurface 21 of the conductors 22 and 23, and a perpendicular strip line 23 formed by filling a via hole disposed perpendicular to the undersurface 21 with a conductive paste. Also, the conductors 22 and 23 have an end 24 powered and the other end 25 grounded.
Further, conventionally, in built-in antennas 10 and 20 as shown in FIG. 1 or 2, a radiating part 2 of the PIFA 10 is modified in its form and a plurality of conductors 22 and 23 are disposed inside the chip antenna to achieve multi-band or wide-band performance. But the conventional built-in antenna is installed in a small size inside a mobile telecommunication terminal such as a mobile phone so that the radiating part 2 of the PIFA 10 is necessarily altered in its form or the conductors 22 and 23 disposed inside the chip antenna 20 is limited in their length. Therefore, disadvantageously, the conventional built-in antennas 10 and 20 hardly process signals of various bandwidths in the mobile telecommunication terminal.